This invention relates to an erythrocyte sedimentation rate (ESR) test which is used as a simple, non-specific blood screening test for inflammatory diseases. The original test was laid out in 1921 by A. Westergren and the basic procedure, in the sense of reading the sedimentation rate of the blood sample, has remained virtually unchanged to date. This ESR test is routinely used in general practitioners' offices, hospital wards and labs to screen for increased inflammatory activity in blood as sort of a basic initial test. Very high ESR values in otherwise non-symptomatic patients may be an indication of such diseases as rheumatic diseases, cirrhosis of the liver, malignant tumors, and anemia. Moreover, the ESR test is routinely used to monitor corticosteroid therapy for rheumatic diseases. Because of this, the ESR test is frequently the first test performed on patients prior to the initiation of other tests.
Originally the Westergren method utilized a blood sample transfer technique in which a syringe was used to obtain a blood sample, and then the blood sample was transferred into reusable glass pipettes. This blood transfer involved the potential hazard to clinicians being exposed to an open blood sample.
Such open blood tests were modified in the past with a device which is described in German Petty Patent No. 26-04-127.4 dated May 15, 1986, which is incorporated herein by reference in its entirety. In that patent, a device is described in which the sedimentation testing process occurs directly in the reagent tube into which the blood sample is initially introduced. For this reason, the reagent tube already contains the anticoagulant substance to be mixed with the blood sample introduced, and is evacuated to facilitate the taking of a blood sample. The device includes an upright frame with a plurality of slots for the introduction of the reagent tubes into the slots. Scales are printed on the face of the frame behind the area where the reagent tubes are positioned in the slots. The clinician, once a sample has been introduced into the reagent tube, and the stopper replaced on the tube, inverts the tube or shakes the tube in order to co-mingle the sample with the anticoagulant already in the tube.
Then, the reagent tube is introduced into the slot provided in the device described. The tube is manually moved in a vertical direction in the slot. The slots or bores are arranged to have a diameter to provide a snug fit for the reagent tubes introduced into them. In this way, the tubes are held frictionally at the vertical level which the clinician positions the tube. By doing so, the clinician may move the tube vertically up and down in order to position the initial upper level of the red blood cells in the sample to be at the zero mark on the scale printed on the frame behind the tube. Then, after an appropriate period of time, usually at one hour and two hour intervals after the introduction of the initial sample, measurements are taken to measure the sedimentation rate of the red blood cell level in the samples introduced into the device.
While such an arrangement is a vast improvement over the original arrangement wherein blood samples had to be transferred from one container to another, thus exposing the clinician to the raw blood sample, such a device still has certain limitations. For example, the printed scale on the upright facing of the device is located behind the reagent tubes when they are positioned for a reading. Since the tubes themselves generally have a diameter of ten millimeters, a very pronounced paralax effect may take place in attempting to read the scale through the tube itself, depending upon what angle the user of the stand tries when reading the values on the scale. Differences of several millimeters are possible which may cause an incorrect reading, as will be understood by practitioners-in-the-art.
Also, moving the reagent tubes up and down within the bore in which they are held in the stand has a tendency to be awkward for certain people and there may be differences in the readings caused simply by variations in production tolerances of tube diameter versus the bores in which the tubes are moved up and down. Also, this variation may be such that the tubes are not held properly at the position required, and any slippage, of course, will modify the final reading obtained. A further minor difficulty has to do with the labeling required for identifying the individual samples in the reagent tubes. Any identification pasted on the tube has the effect of interfering with any readings being taken of the scale positioned behind the tube.
With this invention, by contrast, a new assembly is provided in which the reagent tubes are placed in one or more individual vertically positioned slots. Each of the slots includes a movable sleeve upon which the printed scale for reading the sedimentation rate of the blood sample in the tube is provided. The sleeves are vertically movable, rather than the reagent tubes which the sleeves surround, by a positive drive arrangement in the form of an individual knob for each tube. The individual knobs include a rubber sleeve on the central axial portion or axis of the knob assembly which rubber sleeve engages frictionally with the vertically movable sleeves in the slots to cause them to move upwardly or downwardly depending upon the rotation of the knob involved. A positive drive is provided in such a way that the sleeves move precisely as the knob is turned and are maintained in the appropriate vertical position at which they are set by the user. Thus, the user does not need to move or handle the reagent tube once it is introduced into the slots of the assembly of the invention here. The tube remains positioned as it is and only the vertical sleeve which has an open bottom and which surrounds the tube is moved in order to adjust the scale to the proper level of the sample introduced into the reagent tube initially.
Because of this, there is no variation in the movement of the reagent tube itself, since it never moves once it is introduced into the stand of the invention until the readings are completed. Moreover, because of the precise frictional drive between the adjusting knob and the surrounding vertically movable sleeve, there is no variation in movement once the initial setting has been made. Finally, because the scale is outside the actual reagent tube, there is no variation in the reading of the scale because of any distortion of the view of the reader through the reagent tube as with the prior art. It should be pointed out, finally,that because the reagent tubes are not disturbed or moved in any way during the sedimentation cycle, there is no vibration which would have the effect of distorting the final values obtained from the test procedure.
As purely illustrative of a device of the invention, one may not the attached drawings in which an assembly is shown with ten vertical slots for simultaneously reading ten different blood samples taken from as many as ten different patients, as desired. As will be understood by practitioners-in-the-art, each of the reagent tubes introducers into the assembly shown will have, prior to the introduction of the blood sample, an anti-coagulant material. Generally, this material will be a 0.11 Molar trisodium citrate solution. This will be introduced into each individual reagent tube in a quantity which will provide four parts of freshly collected blood from a patient to one part of the trisodium citrate solution. As will be understood by practitioners-in-the-art, each reagent tube is shaken or inverted so as to mix the anticoagulant material with the freshly collected blood sample prior to introduction into the assembly of the invention for carrying out the sedimentation test.